1. Field of the Invention
The present invention generally relates to RF power distribution systems, and, more particularly, the invention relates to a low loss waveguide feed network for phased array antenna systems.
2. Description of the Related Art
Phased array antennas exhibit desirable properties for communications and radar systems, the most salient of which is the lack of any requirement for mechanically steering the transmitted or received beam. This feature allows for very rapid beam scanning and the ability to direct high power to a target from a transmitter, or receive from a target with a receiver, while minimizing typical microwave power losses. The basis for directivity control in a phased array antenna system is wave interference. By providing a large number of sources of radiation, such as a large number of equally spaced antenna elements fed from a combination of currents of designed phases, high directivity can be achieved. With multiple antenna elements configured as an array, it is therefore possible, with a fixed amount of power, to greatly reinforce radiation in a desired direction.
In order to obtain such directivity, phased array antennas require radio frequency (RF) power distribution systems (also known as feed networks). The feed network losses, the required gain, and the required beamwidth all affect the required antenna size. Current phased array antennas use a variety of RF power distribution networks, such as microstrip or stripline feed networks. Such networks, however, have relatively high losses and thereby increase the size of the antenna array for a given antenna gain.
Therefore, there exists a need in the art for a low loss RF power distribution network for small, low profile phased array antennas.
The disadvantages associated with the prior art are overcome by a waveguide feed network comprising a block assembly having integrated therein a network of waveguides and a plurality of waveguide power dividers. The block assembly includes an input waveguide and N output waveguides. The block assembly can be a split-block assembly formed of either metal or metallized plastic. The waveguides and waveguide power dividers form a waveguide network for dividing the power of a radio frequency (RF) signal present at the input waveguide among the N output waveguides. In one embodiment, the waveguide power dividers are xe2x80x9crat-racexe2x80x9d couplers coupled together in a binary tree formation. The waveguide feed network can function as an N:1 power divider/combiner for use with phased array antenna systems.